Gyroplane rotor starter



Jan.10 ,1939. E DALAND 2,143,688

GYROPLANE ROTOR STARTER Filed A ril 5, 1956 s Sheets-Sheet 1 ATTORNEYS.

Jan. 10, 1939. E, DALAND 2,143,688

GYROPLANE ROTOR STARTER Filed April :5, 1956 V s Sheets-Shee t 2 IN VEN 150R.

ZZZZ'YQZZQZQZ 22M Patented Jan. 10, 1939 PATENT OFFICE GYROPLANE ROTOR STARTER Elliot Daland, Philadelphia, Pa, assignor to Edward Burke Wilford, Philadelphia, Pa.

Application April 3, 1936, Serial No. 72,481

1 Claim.

This invention relates to the starting mechanism used to impart the initial rotative speed to the rotors of rotary wing aircraft and more particularly to the starting of normally aerodynami- 5 cally rotated rotors, as for instance, those used on gyroplanes. However, the scope of this invention is not limited to starting only but contemplates the use of the various drives shown for transmitting small amounts of power from 10 the engine to the rotor at any time or all of the time. It is assumed in all the disclosures that there is an engine which supplies at least a portion of its power to the starting system, and

a rotor which supports a substantial amount of the weight of the craft, and that these are essential parts of a complete aircraft which are not shown because its form is in no way a part of this invention.

In the past the rotors of rotary wing aircraft 20 have been started by a simple clutch, shafting and bevel gears, and the maximum torque in the system was limited by the slipping of a clutch or the shearing of a pin.

The load of starting a rotor consists at first 25 entirely of inertia of the mass of the rotor, but as the'speed increases aerodynamic drag begins to be an appreciable part of the load. At the end of the starting period the load consists almost entirely of drag and the inertia is incon- 30 siderable. Since the weight of the parts must be kept as small as possible, it is necessary to determine the torque required and design all the shafts, gears, and their mountings to stand only that required torque. Then in order to 35 obtain the quickest start it is necessary to maintain that maximum torque for as long a period as possible. This last function is one of the objects of the present invention.

Another object is the disconnection of the 40 drive automatically when the rotor is driven by the air faster than the engine can drive it. This was accomplished in the past by a roller clutch on some such ratchet drive which was usually placed in the shaft between the engine and the 45 pinion gear. Thus when autorotating the rotor was obliged to turn thepinion and some shafting which caused a small amount of friction on the freedom of the rotor.

In the present invention this friction. is elimi- 5 hated and other objects gained as will be understood and appreciated by any one skilled in.

the art by reference to the drawings in connection with the following descriptive matter in the accompanying drawings, forming part of this 55 invention.

Fig. 1 is a diagrammatic side view of a mechanical device for controlling the throttle proportionally with the speed of the rotor.

Fig. 2 is a diagrammatic side view of a pneumatic device for control of the throttle by the speed of the rotor.

Fig. 3 is an enlarged fragmentary transverse section taken thru line AA of Fig. 2.

Fig. 4 is a diagrammatic side view of a mechanical method ofv opening thethrottle to produce constant torque on the rotor regardless of speed.

Fig. 5 is an enlarged fragmentary side elevational view of the torque measuring device used in the device of Fig- 4.

Fig. 6 is a view at right angles to Fig. 5, of one of the torque measuring levers.

Fig. 7 is an end view of the two shaft shown in Fig. 5. v

Fig. 8 is a diagrammatic fragmentary side elevational view of a servo mechanism which both opens and shuts the throttle to obtain constant torque.

Fig. 9' is a fragmentary side view of a device for disengaging the starter drive when rotor is turning faster than the engine can drive it. This device moves the gear axially, similarly to the so-called Bendix? drive.

Figs. 10, 11 and 12 are respectively top, fragmentary, side and bottom views of a device for moving the starter pinion radially in and out of engagement with the rotor gears. 7

Figs. 13, 14 and 15 are respectively top, fragmentary side and bottom views of a modified drive for running a radial disengagement of an 3 extra gear, which allows the starter shaft to stay in the same location.

Referring to Fig. 1, the numeral ll represents the rear part of the engine, l8 the carburetor,

levers and IS the rotor hub. 20 is a large gear attached to V the hub l9, 2| represents the starting pinion, 22 is a pair of bevel gears in train with the pinion gear 2l and ring gear 20. These bevel gears 22 may be eliminated by making gears 20 and 2| beveled. A shaft 23 which is driven by a clutch 24, engages bevel gears 22. The clutch 24 may be mounted on the back of the engine I! and is operated by lever 25 and push rod 35 which is shown in the engaged position.

Attached to starter shaft 23 by suitable links are the weights 26 which move the collar 21 axially against spring 28 as the speed increases.

Collar 21 actuates the upper end of bellcrank 30 up and down along the shaft 23. Bellcrank 30 is attached by pin 3| to another bellcrank 32 which revolves about a fixed pin 33, and whose lower arm is attached to clutch rod 35. The lower arm of bellcrank 38 strikes against a pin 36 on throttle rod 34. This rod 34 actuates bellcrank 31 which moves rod 38 and thus operates the throttle lever 39 of the carburetor l8.

The operation is as follows: With clutch engaged (shownin Fig. l) the lower end of bellcrank 38 engages pin 36, and as speed increases, collar 21 rises, pushing pin 36 forward and .openingithelthrhttle. When rotor is up to speed, 'clutch is disengaged, i. e., pushed forward, which.

rotates bellcrank 32 and raises pin 3| and bellcrank 30 so that its lower end no longer engages the pin 36, then the throttle is fre'e'to use as a hand throttle for controlling the engine in flight. The throttle is closed before the clutch is engaged again for starting. For a constant torque, the power should vary as the speed. thus by proper design of length of arms and linkage, the system can be constructed to a give a very close aproximation to constant torque throughout the entire starting period.

Referring to Fig. 2, the same result is obtained as in Fig. 1, but by a diiferent structure and method. As in Fig. 1, numeral l1 represents the rear of the engine, l8 the carburetor, I9 the rotor hub. 28 is a large gear, 2| a pinion engaging gear 28, 22 a pair of 'bevel gears driving pinion 2|. 23 isa shaft driving gears 22, thru clutch operated by lever 25. Mounted on the shaft 23 is gear 40 driving pinion 4| at fairly high speed. This pinion 4| drives the impeller 42, (Figs. 2 a'nd3) of a centrifugal blower, the casing 43 of which is connected to a cylinder 44 in which isa free moving piston 45, acting against a spring 46, andwhich is attached to rod 41.

The rod 41 is attached to bellcrank 48, rotating on fixed pin 49 and attached to bellcrank 48 are rods 5| attached to the other handle or control,

and rod 58 attached to carburetor throttle arm.

operation is as follows: As the speed of therotor increases, the blower 42 revolves faster and exerts. more pressure on piston 45 which moves downagainst'the spring and opens the throttle. When the rotor is up to speed the throwing out of the clutch 'could be arranged to disconnect rod 4'! from bellcrank 48 and thus the regular hand throttle could be used in flight. By properly proportioning the length of arms, stiffness of spring, and linkages, this system could be made to open the throttle at such a rate that the torque on the rotor would be very nearly constant throughout the starting period.

- Referring to Fig. 4;, the rear end of the engine is represented by 6.9. This may or may not be theengiri. which propels the aircraft. The hub 6|, of the rotary wing system, has a ring gear 62, in which is engaged a pinion 64, driven by bevel gears *thru shaft 66. This is driven thru a torque metering device shown in Figs. 5 to '7 inelusive, by, the-clutch 61 operated by the lever 68 and a rod 69. Referring now to Fig. 5, flange I8 is carried by a rod 52, driven by the clutch 61. It has a number of notches (2 shown) engaging an 'equal number of torque levers ll. These levers may be offset as is shown in Figs. 6 and 7, so that the upper end extends radially from the shaft. These levers ll all bear on a collar 12 slideable on the shaft 66, and collar 12 is held down by a spring 13. The collar 12 has a groove which engages pin 15 on lever 16 which is fixed at pin 11.

On the free end of lever 16 is the pawl 18, en-

gaging ratchet teeth in the bar or ratch 19, which is pinned to the bellcrank 80. This bellcrank 89, is pivotally mounted at 53 and is part of the hand throttle operating system, since attached to one arm is the rod 8|, which operates the carburetor throttle lever 82, and to another arm is attached the rod 83 which is operated by the pilot's hand. The member 84 connects the bar I9 with the clutch rod 69 in such a way that when the clutch is disengaged, the bar 19 is pulled out of contact with thepawl 18. The operation is as follows: With the engine idling and throttle closed the clutch is engaged. This puts bar 19 in contact with pawl 18. A torque load is applied to flange (0 in the direction of the arrow (Fig. 5). This causes levers H to push up on collar I2, compressing spring 13 and causing pawl 18 to move up along bar 19. The rotor starts to turn and in a short time the rotor has acquired sufiicient speed so that the torque with the initial low throttle setting, falls ofi, then the spring expands and pawl l8 catches bar 19 and moves it down until the rotor has absorbed this extra torque. The throttle is opened a little as soon as the torque falls below a set amount and stays in that position until the rotor speed increases and the torque falls ofi again.

This is a device forproportioning the throttle opening accurately to torque regardless of speed.

. In this pawl and ratchet device there is necesof a groove) has a V slot, having upper and lower friction surfaces 54 and 55, in which a conical roller 86 of .friction material is held approximately in a fixed position by shaft 81 and bearings (not shown). This beveled roller 86 drives a worm gear 88 which engages a segment of gear which is attached to or forms part of the bellcrank 98. This replaces bellcrank 80 in Fig. 4, and rods 8| and 83 perform the same functions.

The operation of the modification shown in Fig. 8 is as follows: An increase in torque raises the collar 85 and lower side 55 of V slot engages lower side of conical roller; this spins roller and turns the Worm which tends to close the throttle. At the start the throttle is against a stop so that nothing happens except slippage of the roller. collar 85 moves down until the other side of slot 54 engages roller 86 and causes it to spin in the opposite direction and the worm then opens the throttle. The instant the torque exceeds the required amount collar 85 raises a little and roller 86 slips and stops turning until speed of rotor has picked up and torque fallen off. It then starts turning again opening the throttle more and more as the speed increases.

These two devices (Figs. 4 and 8) protect the clutch, shafting and gears from any excessive torque so they can be designed very closely and operated near this limiting stress. They also insure the torque always being the maximum that the starter will stand and so insure the quickest possible start.

Referring to Fig. 9, the hub 6| of the rotary In a moment the torque falls, then wing system is provided with a ring gear 62 fixed I orv triple thread and this thread 92,

forms a part of the mounting shaft of the pinion 0|. A slight amount of friction is supplied to the pinion by the spring 94 which prevents it from revolving, when the shaft 92 is turned.

The pinion 9| advances upward and its teeth mesh with the teeth of the ring gear 62. It con tinues to advance until it is stopped by collar 93, fixed to its shaft 02, which holds pinion 9| in proper relation to gear 62. The starting of the rotor is then efiectedbut as soon as the air from the take-on urges the rotor to turn faster than the engine wants to turn it, then the gear 62 screws the pinion 9| down on its shaft until it comes out of mesh and the rotor is then perfectly free to turn without the friction of any gears or shafts to impede it. The screwed shaft 93 may be mounted in 2 bearings with a-support 95, or it may be made cantilever from one long bearings The screwed shaft 9! may be driven by bevel ears 65 and shaft 66 from the engine (not shown) as in previous figures in this disclosure, notably Fig. 4. This method of drive may be used in connection with any of the preceding bracket I00 so that in the meshed position proper clearance is maintained between the teeth and in the unmeshed position, the; gear 62 revolves just clear of the teeth of pinion 96.

The action is as follows: Rotation in a counterclockwise direction of pinion 06, assuming a small friction between pinion 06 and link 91, turns link 91 clockwise until teeth are engaged and the driving force which is upward in Fig.. 10 holds pinion Ill-in mesh with gear 62. As soon as the air drives the hub and. gear 62 faster than the engine wants to drive it,'then the direction of this 1 force changes to downward in Fig. 10 and the the drive shaft I02 link 9'! and the pinion is forced out of engagement with gear 62 and it turns perfectly freely. This is a very simple and direct way' of disengaging the drive automatically but it involves moving sideways a small amount which could be allowed for by universals in the shaft. However, in case it were desired to hold the driveshaft still, a modification is shown in Figs. 13, 14 and 15 which accomplishes this. The hub SI of the rotating wing system has attached to its rotating portion a ring gear 62. The pinion gear I03 is driven from the engine by shaft I04 and remains fixed in position. Meshing with drive gear I03 is the idler gear I06, carried by link I05 which link is fixed and swings about shaft I04. Motion of link I05 and gear I00 about shaft I04 is limited, as by allowing the shaft I01 to strike the ends of slot I I 0 in the main supporting bracket I08. In the meshed. or right hand position of the gear I06, the stop allows just the proper clearance for the meshed teeth. In the free or left hand position of gear I 06, its teeth are just clear of the teeth of gear 62. The action is as follows:

counterclockwise rotation of the driven pinion I03, assuming a slight friction between shaft I04 and link I05, causes link I05 to turn counterclockwise. This meshes the teeth of idler pinion I 06 with gear 62 and drives 62 in a counterclockwise direction. The driving force on I06 is upward in Fig. 13, which holds the pinion I06 in mesh with gear 62, but as soon as the air drives 62 faster than the engine wants it to drive it, the direction of the driving tangential force is reversed and isIdownward in Fig. 13. This causes pinion I06 to move out of mesh with gear 62, and

62 can spin freely under theaction of the air.

It is to be observed that the limitation of torque by means of a slipping clutch as proposed heretofore and as used in other arts, is not as desirable as the present method of limiting torque for the following reasons: first, in aircraft, all the machine parts must be designed as small and light as possible and in order to limit the torque by slipping a clutch, power has to be absorbed by the frictional slippage which generates heat. In order to dissipate this heat the clutch has to be of large size and of large heat capacity which runs up the weight and dimensions of the clutci beyond that which is feasible for aircraft. Sec- 0nd, due to the slippage of the clutch, abrasion is bound to occur, which requires frequent re-- newal of-the parts. Third, that it is inefficient from the standpoint of fuel eiiiciency and wear and tear on the engine. vantages are obviated by the invention herein.

I claim:

In rotary wing aircraft, a motor for forward propulsion having a throttle, a rotor, a drive from said motor to said rotor for starting rotation of the rotor, a'blower operatively associated with the rotor in driven relation which produces air pressure varying with the speed of the rotor, a cylinder and piston 'operatively associated with the blower, which is acted on by said air pressure and arranged to open the throttle of the motor as the rotor speed increases so as to provide a substantially uniform torque 'to the rotor while it is beingstarted.

- ELLIOT DALAND.

All of these disad- 

